Large-Format Material Extrusion Additive Manufacturing for Circular Economy Practices: A Focus on Product Applications with Materials from Recycled Plastics and Biomass Waste

Additive Manufacturing has significantly impacted circular design, expanding the opportunities for designing new artifacts following circular economy principles, e.g., using secondary raw materials. Small-format 3D printing has reached a broader audience of stakeholders, including end-users, when dealing with filament feedstocks from plastic and biomass waste. However, using large-format extrusion-based additive manufacturing with recycled feedstocks remains challenging, resulting in limited applications and awareness among practitioners. This work analyzes the most relevant product applications using large-format material extrusion additive manufacturing with recycled plastics and biomass waste feedstocks. It reviews the case studies from 2010 to mid-2024 dealing with new materials and applications from academic research and practical contexts. The applications were analyzed to outline the current situation and trends for large-format 3D printing with recycled plastics- and biomass-based feedstocks, focusing on secondary raw materials, manufacturability, impact on product aesthetics, application fields, and products. Despite more consolidated sectors, new technical applications using granulate feedstock systems, e.g., transportation, are emerging. Academic research studies new secondary raw materials and distributed practices through large-format 3D printing. Practitioners are exploiting different approaches to design products, optimizing building times, costs, and material usage through different manufacturing strategies, strengthening the product identity by highlighting circularity. Spreading specific expertise could enlarge the range of application sectors and products, as well as foster real-world collaborations and scaling-up. Thanks to this work, new synergies between the research and practical contexts can be encouraged for new circular economy practices, detecting and exploring new scraps, material categories, or Additive Manufacturing processes in the future.